Proteases are enzymes capable of cleaving peptide bonds. Acid proteases (i.e. proteases having an acidic pH optimum) have been found to be produced by a number of different organism including mammals and microbes. For instance, microbial acid proteases have been found to be produced by bacterial strains such as strains of Bacillus sp. (JP 01240184), fungal strains, e.g. of Rizopus sp. (EP 72978), Schytalidium sp. (JP 48091273), Sulpholobus sp. and Thermoplasma sp. (WO90 10072) and Aspergillus sp. (JP 50121486, EP 82 395).
JP 3058794 discloses the cloning of a gene encoding an acid protease from R. niveus and the recombinant expression thereof. The cloning and expression of a gene from Cryphonectira parasitica encoding an aspartic protease is described by Choi et al. (1993). Takahashi et al. (1991), Inoue et al. (1991), and JP 407 5586 discloses the cloning of a gene from Aspergillus niger encoding an acid proteinase (Protease A).
Berka et al. (1990) disclose a gene encoding the aspartic proteinase aspergillopepsin A from Aspergillus awamori. The cloning of a gene encoding the aspartic proteinase aspergillopepsin O from Aspergillus oryzae is described by Berka et al. (1993). The cloning of a gene encoding the acid protease (PEPA) from Aspergillus oryzae is disclosed by Gomi et al. (1993).
Acid proteases are widely used industrially, e.g. in the preparation of food and feed, in the leather industry (e.g. to dehair hides), in the production of protein hydrolysates and in the wine making and brewing industry.
There is a need for single-component acid proteases for many different applications, especially in the food and feed industry.